Weakened by radiation, Matt Damon’s character dons an exoskeleton to aid his quest to be cured on board the space station Elysium. Photo: Kimberley French

We were promised flying cars. That’s the refrain you hear from carpers complaining about the lack of technological advancement in their lifetime. Usually as they’re surfing the Web on their iPhone 5 or watching “Battlestar Galactica” on Google Glass while riding in a hybrid taxi.

The truth is that science fiction is not that fictional. So much of what was once a ridiculous, far-flung dream in a book or film has become reality, from the submarine to video chat to genetic engineering.

Now consider “Elysium,” the new sci-fi movie opening Friday from Neill Blomkamp, the director of “District 9.” It’s set in 2154, an age when income inequality has become even more severe than on Manhattan’s Upper East Side. The Haves live in comfortable splendor aboard a massive orbiting space station called Elysium. The Have-Nots are condemned to scratch and survive on the bombed-out, dusty slum known as Earth.

Matt Damon plays an on-parole factory worker who gets irradiated in an on-the-job accident and must find a way to get aboard the space station — where residents enjoy machines that instantly fix all health issues — so he can be cured. Jodie Foster plays Elysium’s icy defense secretary, and Sharlto Copley is her violent, off-the-books operative.

The movie is stuffed with fun, futuristic technology, including bullets that chase their targets and bar codes imprinted on forearms to identify people. While it may seem like pure fiction, much of the film is very much anchored in real science. The Post reached out to researchers and futurists to see just how close we are to really living in Elysium.

“I really do believe that science fiction sets the goals for us,” says Joel Montalbano, NASA’s deputy space station program manager, who did not work on the film. “We think about today, geez, maybe I can’t do exactly what they show in the movie, but maybe I can do a little.”

Exoskeletons: By 2020

After Damon’s accident in the movie, his character becomes weak and near death. To retain his mobility and help complete his mission, he’s given a powered exo-skeleton, which is literally screwed into his body in ghastly fashion.

The power-tool angle might be far-fetched, but exoskeletons are very real and have been around since at least the 1960s, when the military was looking for ways to help soldiers carry more weight.

Today, numerous defense contractors continue to dabble in the world of robotic suits, including Raytheon, which in 2010 unveiled the XOS 2, a hydraulic-powered skeleton that allows its wearer to easily lift 200 pounds repetitively without tiring or punch through three inches of wood.

Syd Mead, a futurist and “Elysium” set designer, predicts that exoskeletons will be reasonably common in a decade — just not necessarily on the battlefield. The first widespread application is probably going to be for the aged and handicapped.

“I’m 80,” says Mead, who is also renowned for his work on “Blade Runner” and “Tron.” “If I had an

exoskeleton to run up and down the stairs, that would be really cool.”

Robotic limbs already exist in use, but before regular people can order up a full Iron Man suit for that wheelchair-bound granny, the price is going to have to drop.

Healing pods: By 2023

We’re almost to that point now. Remember the scanners from “Star Trek”? Bones would scan a body and figure out a blood type. You can do that now with lasers that look through the skin. The military has a blood-analysis lab on a chip and we’re on our way to finding out how things happen on a molecular level with our physiques.

Once you’re working on a molecular scale, you’ve beaten the system and you’re working like nature does. We have already built machines that are barely 50 molecules across.

Researchers at the University of Missouri are experimenting with radioactive nanoparticles that target tumorous cells wherever they may be in the body. When tested on animals with cancer, the small particles were injected into the body and able to seek out the tumors.

Police robots: By 2033

The Earthbound world in “Elysium” is patrolled by an all-robotic police force. No word on what their policy on stop-and-frisk is.

And while we’re still decades away from seeing this become a reality, great leaps have been made in robot technology.

Smaller, non-humanoid robots already help police and the military on the front lines, inspecting bombs and performing other dangerous tasks. Brazil plans to deploy similar bots for the upcoming World Cup.

However, an upright-walking, human-looking robot that can perform the same tasks of a police officer is still many years away.

Boston Dynamics recently unveiled a robot called Atlas, that in appearance, at least, looks a whole lot like the police robots that chase Matt Damon in “Elysium.”

In performance, Atlas is still a bit behind.

“The Atlas robot is considered one of the most advanced humanoid robots ever created, but it presently has the motor competence of a one-year-old child,” reads a statement given to The Post from the Defense Advanced Research Projects Agency, the government division for which the bot was built. “These robots can barely walk; they fall often; they have problems with dexterity; and they’re still learning simple motor skills and are not even close to mastering task-level skills.”

And what of facial recognition, the method by which the robots in “Elysium” recognize criminals? As you probably know, the technology is already here and is around 90 percent accurate at recognizing faces.

Researchers at Michigan State University recently tested the software to see if it was able to pick the Boston Marathon bombing suspects out of crowd videos after the fact. It worked.

Brain downloads: By 2063

Imagine being able to live forever. Not in the way that, say, Larry King or Keith Richards seem to live forever, but by transferring your mind into a computer.

Many thinkers estimate it might be possible in some 50 years.

In “Elysium,” Damon’s brain gets implanted with a computer drive so that he can attempt to plug in and steal information straight out of another man’s noggin.

The trope is familiar to fans of cyberpunk. In William Gibson’s “Johnny Mnemonic,” the protagonist had “hundreds of megabytes” stashed in his head.

“Realistically, by 2050 we would expect to be able to download your mind into a machine, so when you die it’s not a major career problem,” Ian Pearson, head of the futurology unit at British Telecom, told The Observer. “If you’re rich enough, then, by 2050, it’s feasible. If you’re poor, you’ll probably have to wait until 2075 or 2080, when it’s routine. That’s how fast this technology is moving.”

One of the stumbling blocks involves the complexity of the brain, Mead says. Our gray matter is capable of carrying out many processes simultaneously, as hundreds of thousands of neurons fire, reacting to stimuli; computers are generally programmed to work sequentially.

To get the era of downloadable people, a deeper understanding of the brain and memory is required. In February, President Obama announced a $1 billion initiative to create a so-called “Brain Activity Map,” while the European Union has invested $1.3 billion in building a supercomputer replica of a brain.

One of the premises in the original “Elysium” script that didn’t make the final film involved wealthy residents being able to transfer their brains into the body of their choice. Feeling old and run-down? Why not offload yourself into a 20-year-old version of Channing Tatum or Blake Lively?

The day might be coming.

Space Station: by 2113

The Elysium space station is a massive, 15-kilometer-wide wheel on which thousands of the wealthiest citizens live on a terraformed surface designed to look like Beverly Hills. And while a lucky few do now get to spend a few weeks in space, experts say it might be some 100 years until we see anything approaching Elysium.

“Today we do not have the capability,” says Montalbano.

For one thing, it’s a matter of scale. The existing space station is just 357 feet long and barely has enough room to store a few packets of that delicious freeze-dried ice cream, much less hundreds of McMansions.

“It would take an enormous amount of material to build something like that,” says Mead. “This thing is a world unto itself. I would anticipate getting a lot of it from the moon. The moon is rich in metallic ores.”

Another problem: creating gravity.

Many space stations in movies are designed as wheels because rotation is required to create gravity. To keep something like the Elysium spinning at a constant rate, however, would require a complex propulsion system and massive amounts of fuel.

“The cost of that would exceed the benefit,” Montalbano says.

(Though it doesn’t feature into the plot, Mead designed the movie’s station to turn by pumping water around the circle.)

Creating a human-friendly environment is also a major challenge. In “Elysium,” the space station is home to millions of plants and trees that generate oxygen and absorb carbon dioxide. Montalbano says that idea is theoretically feasible, but NASA is nowhere near ready to support human life in space via greenery. The space agency has experimented with growing some smaller plants, such as broccoli, on the space station, but trees are many years off.

Progress, however, is being made. One reality of living in the confines of a space station is that resources are so scarce, almost nothing can be wasted. Including urine. Filtering and recycling techniques have come so far in space that for the astronauts currently up there, today’s pee is tomorrow’s coffee.